Transmission and control therefor



0d 8 i946 w. L. PoLLARD v TRANSMISSION AND CONTROL THEREFOR Filed Sept.13, 1943 2 Sheets-Sheet 1 ...www f Y Oct. 8, 1946. w. PoLLARD vTRANSMISSION AND CONTROL THEREFOR Filed Sept. 13, 1943 2 Sheets-Sheet 2W fm@ Patented Oct. 8, 1946 UNITED STATES PATENT OFFICE TRANSMISSION ANDCONTROL THEREFOR Willard L. Pollard, Evanston, Ill. ApplicationSeptember 13, 1943, Serial No. 502,144

(Cl. 'i4-260) 7 Claims.

My invention relates to transmissions.

This application is a continuation in part of certain subject matterdisclosed in Figs. 1-5, incl., in my co-pending application Serial No.472,314, filed January 14, 1943, now Patent No. 2,378,035.

One of the objects of my invention is to provide a transmission formotor vehicles having automatic means for changing the gear ratiocombined with improved manually controlled means for changing the gearratio when desired.

A further object of my invention is to provid-e such a construction inwhich a foot operated clutch is used for disconnecting the clutch inshifting from forward to neutral and reverse, so that the possibility ofcreeping may be avoided and so that the shifting may be accomplishedquickly.

A further object is to provide such a cons-truction in which a footoperated clutch is used for shifting from high .to second at any desiredtime in going uphill or downhill.

A further object of my invention is to provide a power actuatedfoot-controlled clutch which is also used in the automatic control.

Further objects and advantages of the invention will be apparent fromthe description and claims.

In the drawings, in which two forms of my invention are shown,

Figure 1 is a vertical transmission;

Fig. 2 is a rear end View showing the control for the transmission;

Fig. 3 is a horizontal axial sectional view showing the control;

Fig. 4 is a diagrammatic perspective view showing the control;

Fig. 5 is an axial sectional view showing another form of gearing; and

Fig. 6 is a perspective view showing another form of control apparatus.

aXial sectional view of the General construction Referring to thedrawings in detail, the construction shown comprises a motor shaft afluid coupler having a drive rotor I, keyed to Ithe shaft il, and adriven rotor 2 driven from the rotor I, planetary gearing comprising asun gear 3, a ring gear 4, a planet gear carrier 5, and planet gears Smounted on the gear carrier and meshing with the sun gear and ring gear,a clutch 'I for con'- necting and disconnecting the ring gear 4 withrespect to the drive rotor I, a clutch 8 for connecting anddisconnecting the sun gear 3 lwith respect to the driven rotor 2, abrake mechanism 9 for holding the ring gear 4 against rotation, a brakel0 for holding .the sun gear 3 against rotation, and a dog clutchmechanism II which, in one position, connects the ring gear 4 to thedriven clutch member I 2 and the propeller shaft I3 to the gear carrier5; in another position, connects the ring gear 4 to the propeller shaftI3 and connects the gear carrier 5 to a fixed dog member I4 and, in anintermediate position, disconnects the driven clutch member I2 and thepropeller shaft I3 from the ring gear 4 and gear carrier 5. The drivenclutch member I2 is connected .to rotate with the intermediate shaft I5by means of a iluid transmitting torque transmitting dise I6 secured tothe intermediate shaft I5, a spider or annulus Il secured to the torquetransmitting disc I6, and a tubular shaft I3 secured .to the spider onwhich shaft the driven clutch member i 2 is splined. This tubular shaftI8 is held against reverse rotation with respect to the direction ofrotation of the motor by means of a one-way anchorage mechanism IS. Anantifriction bearing 20 is provided for the tubular shaft I8 The clutchmechanism may be of any suitable type, that shown comprising a controlsleeve 2| rotatable with the driving clutch member 22, a plurality oflevers 23 engaging a channel in the clutch sleeve 2| and pivoted on thedriving clutch member at 24, antifriction rollers 25 mounted on thelevers 23, a bearing ring 26 engageable with the driven clutch plate I2and rotatable with the driving clutch member 22, a spiral helicalcompression spring 21 pressing .the clutch sleeve 2| .to ythe left asviewed in Fig. 1, to -throw the clutch in, a clutch snif-ting plate 23non-rotatably held by means of ribs 29, a thrust bearing 3B between theclutch shifting plate 28 and the clutch sleeve 2 I, a verticalautomatically controlled rockshaft 3| and a shifting yoke 32 mounted onthis shaft engageable with the clutch shifting plate 23 vfor moving theclutch sleeve tothe right to throw `the clutch out.

'I'he brake mechanism 9 comprises a brake plate 33 splined on .thetubular shaft I8 and engaged by the clutch shifting plate 28 Vwhen theclutch is thrown out to clamp this brake plate 33 between Ithe clutchshifting plate 28 and a braking surface 34 on the housing.

The clutch shifting yoke 32 is controlled by means ofthe vacuum operatedcylinder and piston mechanism 35 (Figs. 2, 3, and 4), the piston rod 36of which is connected with a lever 3l secured to the rockshaft 3| onwhich the clutch shifting yoke 32 is mounted.

The clutch mechanism 8 for controlling the connection and disconnectionof .the sun gear 3 with respect to the driven rotor 2 is iny generalsimilar to the clutch construction just described comprising a drivenclutch plate 33 connectible and disconnectible with respect to .thedriving clutch member 39 by means of a clutch shifting yoke 40. Thedriving clutch member 39 is keyed to a tubular shaft 4|, which shaft iskeyed to the driven rotor 2 of the hydraulic coupler. brake mechanism Iis similar to the brake mechanism 9 associated with .the front clutchand, when applied, holds the brake plate 33 which is splined on .thetubular shaft 42 against rotation. The sun gear 3 is secured to thistubular shaft 42 and the driven clutch member 38 is splined thereon. Aone-way anchorage device 43 is provided for holding the sun gear 3against reverse rotation with respect to the direction of rotation ofthe driving clutch member. An antifriction bearing 44 is provided forthe Itubular shaft. The rockshaft 45 on which the clutch shifting yoke45 is mounted is subject to two controls, one controller being the pedal41 which has a lost motion connection at 48 with the rockshaft 45 onwhich the clutch shifting yoke is mounted and the other controllercomprising a power operated cylinder and piston mechanism 49, the pistonrod 50 of which has a the rock arm 52 secured .to .the rockshaft 45.

General operation In considering the cperation, it is `to be borne inmind that when the front clutch 1 is in, the front brake 9 is off andthat when the front clutch is out, the front brake is on, and similarly,with respect to the rear clutch, that when the rear clutch 8 is in, therear brake I0 is oir, and when the rear clutch is out, the rear brake ison. It is also to be borne in mind that when the iront clutch 1 is in,lthe ring gear tate with the driving coupler rotor l, and that when thefront clutch is out the ring gear is held against rotation by the frontbrake 9; also, that when .the rear clutch 8 is in, the sun gear 3 isconnected to rotate with the driven rotor 2 of the hydraulic coupler,and that when the rear lclutch is out, the sun gear is held againstrotation by the rear brake mechanism I0. With this construction, it willbe seen that when the rear clutch 8 is in and the front clutch 1 is out,.the sun gear 3 will be connected to rotate with the driven rotor ofthehydraulic coupler and the ring gear will be held against rotation by thefront brake, giving a low speed gear ratio which may be around .3; thatwhen the front clutch 1 is in and V.the rear clutch 8 is out, the ringgear 4 will be connected to rotate with the drive rotor I of thehydraulic coupler and the sun gear 3 will be held against rotation by.the rear brake for intermediate speed gear ratio which may be around.'1, and that when both the front clutch and the rear clutch are in, thesun gear will be connected to rotate with the driven rotor of thecoupler and the ring gear will be connected to rotate with the driverotor of the coupler, giving substantially direct high speed. Thisgeneral construction is similar to .that shown in my co-pendingapplications Serial Numbers 410,815, 462,356, and 472,314.

Control of clutches and brakes The lost motion connection with 4 isconnected to roi pressure in the intake manifold. For this pui"- pose,suitable valves are provided in the conduits leading from the cylindersto the manifold. These include a manually operated valve 55 (Fig. 4)which can be operated to shut off all communi cation between thecylinders and the manifold, a solenoid controlled valve 55 foralternatively placing the sun gear controlling cylinder in communicationwith the manifold or with .the atmosphere, a similar solenoid operatedvalve 51 controlling communication between 4the ring gear controllingcylinder and the manifold and atmosphere, and a solenoid operated valve58 in parallel with the solenoid operated valve 51 also controllingcommunication between the ring gear controlling cylinder and themanifold and atmosphere. The solenoid 59 controlling the valve 56 may becontrolled both by the automatic controller 60 and by the pedal-operatedcontroller 8|. The automatic controller 60 may be of any suitable type;for example, such as shown in my co-pending application Serial No.401,162, led July 5y 1941. The solenoids 59 and 62 which control the sungear cylinder 63 and ring gear cylinder 54, respectively, may besimultaneously energized by the automatic controller 68 through thecontact E5, thus simultaneously placing both cylinders 63 and 64 incommunication with the suction manifold. The solenoid 66 which alsocontrols the ring gear cylinder 64 is energized by engagement of theautomatic controller contact E1 with the contact 68.

Referring rst to the fully automatic .control for the gear ratiochanges, when the automatically controlled pivoted contact 61 is not inengagement with either of the contacts 55 or 68, the solenoids will allbe deenergized and the front clutch 1 will be out, the front brake 9will be on, the rear clutch 3 will be in, and the rear brake I0 will beoff. The coil compression spring 68a, acting between an abutment 68h onthe casing and a shoulder 68e on the piston rod 36, will hold the clutch1 out and the brake 9 on, as may be seen from Figs. 3 and 4. This willresult in low gear.

When the automatic control contact 61 engages the contact 65, thesolenoids 62 and 59 will both be energized placing both cylinders 63 and64 in communication with the exhaust. This will throw the front clutchin, connecting the ring gear to rotate with the motor shaft and willthrow the rear clutch 8 out and the rear brake l0 on, holding the sungear against rotation, thus giving intermediate speed. When conditionsbe- -come such that the contact 61 automatically engages the contact 68,the solenoids 59 and 62 will be deenergized but .the solenoid 65 will beenergized to maintain communication between the cylinder 84 and thevacuum to Vhold the front clutch 1 in engagement. When the solenoid 59is deenergized, the rear clutch spring 21 will 4throw' the rear clutch 8into engagement, thus connecting the sun gear to rotate with the drivenrotor 2. This condition will give substantially direct drive.

It will be seen that when the car is in direct drive, it can be placedin intermediate drive at any time, simply by pressing down on the.clutch pedal 41, disconnecting the rear clutch 8 and placing the brakeID in ori-condition, thus holding the sun gear 3 against rotation. Thelost motion connection 5| between the lever 52 and the piston rod 50enables the `clutch to be thrown out quickly without waiting for .theaction of the piston 54, although if the clutch pedal 41 is depressedgradually, the piston 54 will keep up with the lever 52 and do theactual work of .throwing the clutch out and applying the brake. This isaccomplished by means of the live contact 69 on the pedal op-` eratedcontroller 6I which, when the pedal 41 is depressed, engages the contact'I5 on the arm 52 which contact 'I0 is connected with .the solenoid 53.This will require only slight pedal pressure as the actual work will bedone by the piston 54.

For reverse, the clutch pedal 41 is depressed to throw the clutch 3 outand the reverse dog clutch mechanism II is shifted rearwardly as viewedin Fig. l. This may be accomplished by a manually operated shifter yoke(not shown) and engaging the outer clutch sleeve `'I3 which carries withit the inner :clutch sleeve 14. In this position, the gear carrier 5 isheld against rotation and the ring gear 4 is connected to rotate withthe propeller shaft I3.

The connection from the ring gear to the propeller shaft is through theclutch sleeve '14, the front teeth 'i3 of which engage the clutch sleevel5 and the rear teeth 'l2 of which engage the clutch ring 'l5 on thepropeller shaft E3. The gear carrier 5 is held against reverse rotationby the clutch sleeve 1S, the front teeth 18 of which engage the clutchring 33 on the gear carrier and the rear teeth 'il of which engage theteeth 3i on the fixed ring Id. Under these conditions, the sun gear 3 isdriven from the turbine rotor 2 through the clutch S, the gear carrier 5is held against reverse rotation, and the ring gear 4 and propellershaft i3 are rotated in a reverse direction at relatively low speed.

When the clutch assembly l i is in forward position, the ring gear 4 isconnected with the intermediate shaft I5 through the clutch sleeve 'I4and the gear carrier 5 is connected with the propeller shaft I3 throughthe clutch sleeve '19.

The construction sho-wn in 1Fig. 5, which may be substituted for thereverse mechanism shown in Fig. l, enables four forward speeds andreverse to be obtained. The gears 32, 83, and 35 correspond to the gears3, d, and 6 of Fig. l. The low, second, and third speed may be the sameas that described in connection with Figure 1. For fourth speed, oroverdrive, the dog clutch construction shown is used. This comprises atoothed clutch member 38 keyed to the gear carrier ed, a toothed clutchmember S3 keyed to the ring gear 33, a toothed clutch member 35 alsokeyed to the gear carrier, a toothed clutch member Q2 keyed to theintermediate shaft I5, a toothed clutch member S3 keyed to the propellershaft I3, a clutch sleeve 9i having clutch teeth 9d slidable in theclutch member 92 and also having clutch teeth 95 which, in one position,engage the clutch member 33 and, in another position, engage the clutchmember SS, a second clutch sleeve 5G surrounding the iirst sleeve havingclutch teeth 3Q slidable in the clutch teeth of the clutch member t3 andhaving teeth 8l' which, in one position, engage the teeth of the clutchmember S8 and, in another position, engage the teeth of the clutchmember 93.

A groove provided for engagement with the shifting arm Si?! ov thecentrifugal control apparato-s, le c "ifugal control mechanism comprisesa slee/e 9? splined on the propeller shaft I3, a plurality of arms 33rotatable with the sleeve Si', weighted arms 3d pivoted at I0@ on the33, rockable with the arms mi, springs 52 acting against the centrifugalforce of the weighted arms and stops IGS and Idd for limiting themovement of the arms. The sleeve 3? may be shifted longitudinally of theshaft by a suitable manually operable' shifter yoke (not shown).

, shaft I5.

6. When the dog clutch mechanism is in the left-y hand position, asshown in Fig. 5, the clutch sleeve 86 connects the cage 84 with theshaft I3 and the sleeve 9| connects the ring 83 with the When the dogclutch is moved to the right-hand position, the sleeve will connect thepropeller shaft I3 with the ring gear 83 and the sleeve 9i will connectthe gear carrier 84 with the shaft I5 through dog clutch 9E. Thisposition of the dog clutch maybe used for shifting between third andfourth speed and for reverse. lThis construction may in general besimilar to that shown in my co-pending application Serial No. 462,356,filed October 17, i942, now Patent No. 2,353,004.

A5 indicated above, in this position the gear carrier 84 is connectedWith the shaft I5. For reverse, the shaft I5 is held against rotation bythe brake 5v to hold the gear carrier 34 against rotation, and the sungear is connected to rotate with the turbine 2 by means of the clutch 8.This causes reverse rotation of the ring gear 84 and the propeller shaftI3.

When the car speed is high enough so that the centrifugal force devicecan exert force sufficient to shift the sleeves 86 and -3I rearwardlywhen permitted to do so, the planetary gear members are brought intosynchronism and the rearward shift of the sleeves 86 and Si takes place.This synchronism may be elfected in various ways; for example, ybyallowing the accelerator pedal to rise slightly to slow down the motorspeed while the car speed continues substantially the same. Thisrearward shift of the sleeves 83 and Si connects the shaft I5 with thegear carrier 84 and connects the propeller shaft I3 with the ring gear83. For overdrive, the brake 9 is released, the clutch 'i is connected,the clutch 8 is released, and the brake Iii is connected. Under theseconditions the gear carrier 36 is driven from the clutch "l, the sungear 32 is held against rotation, and the ring gear 33 and propellershaft I3 are driven at a speed greater than that of theV gear carrier.With these connections, overdrive may be obtained by depressing thepedal di? to hold the sun vgear against rotation, and third speed(substantially direct drive) can vbe obtained by releasing the pedal ilto throw the clutch 8 in and connect the sun gear S3 to rotate with theturbine rotor 2.

If it is desired to go into reverse, the car is brought to a standstill,in which conditionthe solenoid's SI5 and S2 will be deenergized and thefront brake 3 will be on. The pedal d? is then depressed to disconnectthe clutch and the sleeve 9'! is shifted rearwardly by any suitablereverse lever to connect the gear carrier 8d with the shaft I5 and toconnect the ring gear 83 with the propeller shaft I3. The pedal 4l isthen released and the clutch 8 connects the sun gear 32 to rotate withthe turbine rotor 2. Under these conditions, the gear carrier 8d is heldagainst rotation by the braise 9, the sun gear 82 rotates with theturbine rotor, and the ring gear and propeller shaft are rotatedreversely with respect to the rotation of the turbine rotor 2.

With the pitch ratio of 3:7 of the sun gear and ring gear, thisconstruction gives four forward speed ratios of approximately .3, .'TI,1 and 1.4 and a reverse speed ratio of .4.

The spacing of the clutch teeth rings of the d-og clutch member-s, 14,79, 33, 8i, 38, 35 and 36, both in Fig. l and'Fig. 5, may be such thatin intermediate position of the clutch members they will be in neutralposition with nodrivingfcon` 7 hection with the dog clutch members'h'.I, 'i6 and 8l so that the transmission can be placed in neutral andthe motor allowed to run with no danger of creeping of the car.

It will be noted that in second and fourth gear ratio, all of the poweris by-passed around the hydraulic drive and that in third gear, 'I0 percent of the power is by-passed. Also, that the drive may be disconnectedat any time simply by depressing the clutch pedal 41 far enough to throwthe clutch 8 out; that a power device is provided which avoids thenecessity for much foot power in throwing out the clutch 8; that thispower device is used in the automatic control, and that in starting,either in forward or reverse, the smooth action of the hydraulicflywheel is utilized.

Fig. 6 shows a form of control apparatus which may be used instead ofthat shown in Fig. 4. In this form, the clutch shifting yoke-3 32 and 45and the power actuator 35 may be substantially as 'shown in Fig. 4 andmay be used to control substantially the same transmission as that shownin Fig. l. In this form, the power piston 53 is connected so that whenit moves, to the right, it will operate the lever 31 and rock shaft 3|to cause the clutch shifting fingers 32 to move to allow the clutch l2to connect the ring gear to the power input and so that it will causethe button |05 on the piston red 36 to engage the yoke |06 on the rockarm Hl to rock the rock shaft |08 and the hook lever |09 which engagesthe hook H on the tiltable latch pedal IH to rock the sleeve H2 and theclutch fingers 45 to throw the clutch plate 38 out to disconnect the sungear 3. This throwing in of the ring gear clutch and throwing out of thesun gear clutch will Shift the transmission from low to second.

The latch pedal l l I is pivotally mounted on the pedal lever H3 at l I4and is normally biased toward latching position with the hook H on thepower lever |09 by means of a coil compression spring H6. To disconnectthe clutch pedal HI from the power lever H29, it is only necessary topress down on the lower end of the tiltable latch pedal l Il to tip thepedal hook Htl upwardly out of engagement with the hook H5 on the powerlever |99. When the pedal I Il is disengaged from the power lever IBS,the pressure on the foot pedal can be relieved to let the sun gearclutch in, thus shifting from second to third speed.

At low speeds, before the speed control of the power actuator 35 causesit to act, the clutch pedal Hl may be used in the ordinary manner forconnecting and disconnecting the sun gear with respect to the powerinpnt.

Further modifications will be apparent to those skilled in the art andit is desired, therefore, that the invention be limited only by thescope of the appended claims.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. A variable speed transmission and control therefor comprising a threespeed forward planetary transmission including a sun gear, a ring gear,a gear carrier and planet gearing mounted on said gear carrier andmeshing with said sun gear and ring gear, clutch means for connectingsaid sun gear with the power input, clutch means for connecting saidring gear with the power input, means for holding said Isun gear andring gear against reverse rotation when not connected with the powerinput, means controlled by speed for automatically disengaging the sungear clutch and holding the sun gear against reverse rotation andengaging the ring gear clutch for shifting from low to second speed, andmanually controllable means for engaging the sun gear clutch forshifting from second to third speed.

2. A variable speed transmission and control therefor comprising a threespeed forward planetary transmission including a sun gear, a ring gear,a gear carrier and planet gearing mounted on said gear carrier andmeshing with said sun gear and ring gear, clutch means for connectingsaid sun gear with the power input, clutch means for connecting saidring gear with the power input, means for holding said ysun gear andring gear against reverse rotation when not connected with the powerinput, means controlled by speed for automatically disengaging the sungear clutch and holding the sun gear against reverse rotation and forengaging the ring gear clutch for shifting from low to second speed, andpedal controllable means for engaging the sun gear clutch for shiftingfrom second to third speed.

3. A variable speed transmission and control therefor comprising areverse and three speed forward planetary transmission including a sungear, a ring gear, a gear carrier and planet gearing mounted on saidgear carrier and meshing with said sun gear and ring gear, clutch meansfor connecting 'said sun gear with the power input, clutch means forconnecting said ring gear with the power input, means for holding saidsun gear and ring gear against reverse rotation when not connected withthe power input, means controlled by speed for automatically disengagingthe sun gear clutch and holding the sun gear against reverse rotationand for engaging the ring gear clutch for shifting from low to secondspeed, manually controllable means for engaging the sun gear clutch forshifting from second to third speed, a driven shaft and connecting anddisconnecting power path shifting means which in one position connectsthe ring gear with the driven member of its clutch and in anotherposition connects it with the driven shaft, and which in one positionconnects the gear carrier with the driven shaft and in another positionholds the gear carrier against rotation.

4. A variable speed transmission and control therefor comprising areverse and three speed forward planetary transmission including a sungear, a ring gear, a gear carrier and planet gearing mounted on Saidgear carrier and meshing With said sun gear and ring gear, clutch meansfor connecting said sun gear with the power input, clutch means forconnecting said ring gear with the power input, means for holding saidIsun gear and ring gear against reverse rotation lwhen not connectedwith the power input, means for engaging the sun gear clutch anddisengaging the ring gear clutch for low speed, means for disengagingthe sun gear clutch and engaging the ring gear clutch for shifting fromlow to second speed, and for engaging the sun gear clutch for shiftingfrom second to third speed, a driven Shaft and connecting andYdisconnecting power path shifting means which in one position connectsthe ring gear with the driven member of its clutch and in anotherposition connects it with the driven shaft, and which in one positionconnects the gear carrier with the driven shaft and in another positionholds the gear carrier against rotation.

5. A variable speed transmission and control therefor comprising a threespeed forward planetary transmission including a sun gear, a ring gear,a gear carrier and planet gearing mounted on said gear carrier andmeshing with said sun gear and ring gear, clutch means for connectingsaid sun gear with the power input, clutch means for connecting saidring gear with the power input, means for holding said sun gear and ringgear against reverse rotation when not connected with the power input,means for engaging the sun gear clutch and disengaging the ring gearclutch for low speed, means for disengaging the sun gear clutch andengaging the ring gear clutch for shifting from low to second speed andfor engaging the sun gear clutch for shifting from second to thirdspeed, said clutch means and holding means comprising two power drivendriving clutch pressure plates, one for the sun gear and one for thering gear, two nonrotatable Ibrake pressure plates, one for the sun gearand one for the ring gear, two control elements shiftable longitudinallyof the axis of Said planetary transmission, and means controlled by oneelement for alternatively rendering the sun gear clutch pressure plateand the sun gear brake pressure plate eiective and means controlled bythe other element for alternatively rendering the ring gear clutchpressure plate and the ring gear brake pressure plate effective.

6. A variable speed transmission and control therefor comprising a threespeed forward planetary transmission including a ysun gear, a ring gear,a gear carrier and planet gearing mounted on said gear carrier andmeshing with said sun gear and ring gear, clutch means for connectingsaid sun gear with the power input, clutch means for connecting saidring gear with the power input, means for holding said sun gear and ringgear against reverse rotation when not connected with the power input,means for engaging the sun gear clutch and disengaging the ring gearclutch for low speed, means for disengaging the sun gear clutch andengaging the ring gear clutch for shifting from low to second speed andfor engaging the sun gear clutch for shifting from second to thirdspeed, said clutch means and holding means comprising a power drivendriving clutch pressure plate for the sun gear, a nonrotatable brakepressure plate for the sun gear, a control element shiftablelongitudinally of the axis of said planetary transmission, and meanscontrolled by Saidicontrol element for alternatively rendering the sungear clutch pressure plate and the sun gear brake pressure plateeiective.

7. A variable speed transmission and control therefor comprising a threespeed forward planetary transmission including a sun gear, a ring gear,a gear carrier and planet gearing mounted on said gear carrier andmeshing with said sun gear and ring gear, clutchmeans for connectingsaid sun gear with the power input, clutch means for connecting saidring gear with the power input, means for holding said sun gear and ringgear against reverse rotation when not connected with the power input,means for disengaging the sun gear clutch and engaging the ring gearclutch for shifting from low to second speed and for engaging the sungear clutch for shifting from Second to third speed, said clutch meansand holding means comprising a power driven driving clutch pressureplate for the ring gear, a nonrotatable brake pressure plate for thering gear, and a control element shiftable longitudinally of the axis ofsaid planetary transmission, and means controlled by said controlelement for alternatively rendering the ring gear clutch pressure plateand the ring gear brake pressure plate elective.

WILLARD L. POLLARD.

